Signaling system for telephone trunk-lines.



PATBNTED MAY 8, 19.06

M. S. OONNER. SIGNALING SYSTEM FOR TELEPHONE TRUNK LINBS.

APPLIOATION FILED APR. 9, 1900. RENEWED OUT. 5, 1905.

.-=""traneous current is like y to find a circuit UNITED STATES PATENT OFFIOE.

uEaRI'rr s. OONNER, OF CHICAGO, ILLINOIS, AssIcNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIF SIGNALING SYSTEM FOR TELEPHONE TRUNK-LINES.

Specification of Letters Patent.

Patented May 8, 1906.

Application filed April 9,1900. Renewed'Octcbonfi) 1905. Serial No. 282,063.

- adevice for preventing interference with the operation of. the signals by currents'arising" from sources. foreign to the signaling-circuit, such as differences of potentia in the earth at the diflerent exchanges, also for preventing interference with conversation by currents of such periodicit as to cause audible vibrations in the te ephone-receiver, which arise from any difference in the electrical conditions of the earth at the different exchan es or from inductive action upon imperfect ybalanced lines. I

It is Well known in the art of telephony that in the vicinity of electric railways or other systems ofelectrical appliances employing electric currents and connected at various points with the earth differences of electrical potential are found at diff cut 10- calities, which of course produce or 'end to produce currents through conductors, such as telephone} lines, which happen to connect these different points. The differences of potential between different localities in the in telephone-exchanges.

vicinity of electric railways or other electric circuits employing grounded returns not infreq ently rise above the electromotive' fprc s commonly used for si naling purposes encc when two.

exclian es are connected by a metallic trunk I I over -w 'ch, due to the present state of the art, it is necessary to operate two separate signals, and when this is a ccomplished by "employing each conductor for a-separate circuit having return throu h the earth, the exthrou h the trunk-line from one exchange to z the ot er and operate the signals associated with the trunk-line circuit. As these signals 59 be occasioned by suchinterference. Also in such trunk-lines having a ground ateach end considerable trouble is experienced in some localities on account of interference sounds or noises on theline, which greatly impairs telephone conversation. This is due either tof the proper frequency of.the currents arisinductive circuit,, for if its'two ends are grounded each" conductor with its return ground forms a muti ially-inductive circuit with every other circuit havingthe same return.

By the circuits and apparatus of my invention the usual automatic signaling over trunklines can be accomplished and interference from'extraneous currents avoided. This is preferably done without employing the earth as a part of the si naling-circuits, though ground-return signa ing-circuits may be used without departing from some features of-my invention. I

Generally speaking, the preferred embodiment of my invention consists in a, circuit containin a source of electrical energy and two signa s, with means for controlling the operation of such. The first of these signals (or means for controllin 'a signal) is of such electrical resistance and construction that when the two are placed in the circuit with the source of electrical energy it will permit of-the passage of enough current to be operative itself, but not of enough to operate the second signal.

Myinvention consists, further, of means for shunting the high-resistancesignal (or means for controlling a signal) so as to permit enough current toflow to operate the second signal,-while at the same time maintaining the shunted signal in its operative condition.

My invention also contemplates suitable means for opening the above circuit or otherwise rendering the high-resistance signal inert, also of means for opening the'above circuit or of placing in it enough resistance to permit of the non-operation of the first signal.

Other embodiments of my invention may ICC ' trunk-line 14$. 15.

' r oi the magnet 1'.

be readily made without departing from its spirit.

I will explain my invcn tion more particuularly by reference to the accompanying drawing, which, illustrates so much of a tele-,

phone-exchange system. necessary to understand the application of the invention.

A and A are two substations, each provided with the usual receiver a, transmitter a switch-hok a call-bell a and condenser a. These stations are connected by lines 1 and 2 to spring-jacks d in exchanges C and D, respectively. At the central ollice 0 there are a pair of switch-plugs j and j, which are provided with the proper terminals to engage the contact parts d, (P, and d of the jack 6! and the contact-pieces m, m, and m of the jack m. Conductors 7 and 8 connect the central battery 0 with the tin and ring of the answering-plug j, while conductors 9 and connect the same battery with the tip and ring of the connecting-plug j. Windings n and of a repeating-coil are included in circuit with conductors 7 and 8, while other windings a and n of the same coil are included in circuit with conductors 9 and 10. Conductors S and 1.0 also include the helices of the magnets Z and Z, which are provided each with an armature and contact-anvil, which control the supervisory signals 7c and 7c, respectively. The pair of switching-cords would, of course, also be provided with the usual listening-key for connecting the operators telephone with. the circuit.

Between the ollices C and D extends a This trunk-line terminates at the ollice' U in a springiack m,'provided with contact-pieces for engaging the connecting-plug at C. At the station D the trunk-line includes in circuit the windings p and p of a repeating-coil p and the winding 2" of the magnet 'r, with the condenser c bridged across The winding r, should be of very high resist-- ance-say ten thousand ohms, Associated with windings p and p are windings p and p of the same coil,'which are included in the circuit with the central battery 2, through the conductors l6 and 17, which include also the winding of the magnet q and the ringing key 00, and terminate in the tip and ring contact-pieces ol" the plug 1 A shunt-circuit composed of the contactanvil and armature of the magnet g, the winding 5 ol the magnet s, and thewindin'g r "of the magnet r is placed around the wind ing Magnet '1' is provided with a contact-anvil and an armature, which, together with'thc contact-anvil and armaturc ol the magnet t, control the disconnecting-signal o. l vlagnet s is provided with a contact-anvil, an armature, and a winding 3 which, together with the term iual oi the plug 'y and the contact-piece of the ack (Z, control the ringing-signal u. The association of the repeating-coils and central battery; together with the key, ringing-generator, the ringingsignal a, and means for operating it shown, 1s well known to those skilled in the art.

I have not deemed it necessary to show an operators telephone outfit, as its association with the cord-circuit is well understood by those skilled in the art.

Having thus particularly described the details of one embodiment of my invention and a telephone system in connection with which the same is adapted to be employed, I will now describe the operation thereof.

Let it be assumed that subscriber at'staion A demands connection with station A of oflice D. After receiving the call by means of line-signalfin the usual way, inserting the plug into the spring-jack J, and receiving orally the order of thesubscriber at station'A the operator at ofiice C inserts plug 1' into the spring-j aclr m and at the same time by means of the order-wire circuit 18-19 requests the operator at the o'fiice D to connectthe trunlo. line terminating at the oilice D in plug 1] with the line to the required station A. l Vhen the operator atQC places plug 7' in spring-jack d, the central battery 0 finds circuit through the contact-pieces of the plug and jack (Z onto the line 1 2, and the receiver a being taken from the switch-hook c the contact at" is closed, thus energizing magnet Z, closing its contact, which shunts out the signal It, although its circuit has been completed hy means of the plug 31' and the spring-jack d through the winding of ma at a to the battery 0. When the plug 9' inserted in the spring-jack m, the battery 0 finds a circuit out over the line 14 15 through windings and p of the repeating-coilp and the winu ing 1" of magnet 1 energizmg that magnet and closing the contact r The winding r of magnet 1", however, is or so great electrical resistance that it does not allow enough cur rent to flow in the circuit to enegrze the magnet Z sufficiently to close its contact. The signal 70 therefore remains dis la ed, its circuit having been completed wit vt e battery 0 through the plug j and the spring-jack m. When the plug y. is inserted into the spring-jack d, the signal a is displayed, its circuit being completed. with the battery g, through the winding of magnet t, the plug y, the jack d, and the winding of magnet e. The circuit of the signal 1) is also completed by the closing of the contact t, due to the energizetion of the magnet i. The signal v, however, is not displayed, owing to the maintenance of the shunt 21 about it by the closed contact r. The operator at oflice D then calls the station A by means of the generator w,-

the key m, and the call-bell o 'Whenthe subscriber at station A removes the receiver a from the hook a the contact a is closed. The closure of the contacts completes the c1rthe contact q. The contact q in turn places a comparatively low resistance shunt composed of the winding 8" of the magnet s and of the winding of the magnet 7" around the winding 1" of the magnet 1', permitting the passage of enough current over the trunkline from the battery to energize the magnet l sufficiently to close its contact, thus shunting out the signal it" by the shunt 22 23. The armature of the magnet 7' is still attracted, partly in virtue of the resistance in the shunt and partly because the winding r energizes by the current which passes through the shunt. At the same time the magnet sis enby the winding 8 and closes the conwhich in turn shunts out the signal it by the winding 8 Also the contact 8 is maintained by the winding 8 until the withdrawal of the plug 'y from the jack (1 irrespective of the subsequent condition of winding 8. When the subscribers have finished talking, the receiver a at A is hung on switchhook 00 thus opening the contact a, which in turn deenergizes magnet Z, allowing its contacts to open the shunt which they control, thus displaying signal is, In the same manner the subscriber at A effects the open ing of the contact (1 at office D, whereby the low-resistance shunt of the winding 1" of the magnet '1" is removed, thus sufficiently denergizing Z to permit of the opening of its contacts, which permits of the displaying of signal Isby the removal of the shunt 22 23. Observing the signals and k, the operator at C removes plug' i from the spring-jack d and plug y" from spring-jack m. The lastmentioned act deenergizesmagn et 7', allowing contact 1' to open, remoying the shunt 20 21 from the signal 1) and causing its display. The display of the signal '1) instructs the operator at D to take down the plug y, which act restores the signal 1) to its normal condition by the opening of contact If, due to the deencrgization of the magnet t.

o the claims I use the term signaling instrument in the sense of any electromagnetic signaling device or any electromagnetic means'for controlling a signaling device.

It is obvious that the shunt-circuit around the winding r of the magnet 1* may be open ed and closed by any other means than the magnet q that this shunt need not consist of the winding 5- of the magnet s and the winding 1" of the magnet '1', but may be any other electrical resistance, and that it need not consist of or contain a Winding on the magnet 9". It is also obvious that the magnet 7" may be deenergized in other ways than opening the circuit including the same. I therefore do not wish to be limited. to ism and system of circuits but,

Having described my invention, 1 claim as new, and desire to secure by Letters Patent,

together with all modifications; that may be ergized tact 8,

herein described line being severed ing a source of energy,

the precise mechanmade by those skilled in the art, the follow- 1. The combination with telephone-lines and a trunk-line for uniting them, of a signal in the trunk-line and a source of current in a bridge thereof at one terminal station a repeating-coil at the other terminal, said trunkand having its severed terminals united through the windings of the repeating-coil to form two conductivelys eparated but inductively-continuous circuits, and a high-resistance signal-controlling magnet in the portion of the trunk-line leading to the first-mentioned office, the said resistance being sufficient to prevent the operation of the signal in the circuit therewith; a source of current and a relay-magnet in the other portion of the trunk-line adapted for connection with the called line, and a shunt of the high resistance signal controlling magnet controlled by said relay, as described.

2. The combination with telephone-lines having switches adapted to close the'line-circuits while the telephones are in use, said lines entering different central oilices, and a trunk-line for uniting said lines; a supervisory signal in the trunk-line and a source of current in a bridge thereof at one of the offices; a repeating-coil at the other office, the trunk-line thereat being severed, the terminals of the wires leading to the first-mentioned station being united through one set of windings of the repeating-coil, and the terminals of the wires adapted for connection with the called line being united through the other set of windings of the repeating-coil,

and a source of current and a relay in the last mentioned portion of the trunk-line; a highresistance magnet in the trunk-line in circuit with the aforesaid supervisory signal, a clearing-out signal controlled by said high-resistancemagnet, a shunt about said high-resistance magnet, and an auxiliary winding of the magnet therein, said shunt being controlled by the relay in the other portion of the trunkcircuit, substantially as described.

The combination with a trunk-line hava signaling instrument and means for closing the circuit at one terminal station, of a higi -resistance signaling instrument bridged across the line at another terminal station, a'telephone-line, provided with a switch at the substation for closing the iine, in connection with the trunk-line, and a shunt-circuit controlled by the switch at the telephone-substation around the winding of said high-resistance signaling instrument, whereby the first terminal station of the trunk line is responsive to the opening and closing ofthe switch at the subscribers substation without interfering with the operation ofthe high-rethe signaling instrument at 1 sistance signaling instrument, substantially as described.

cord containing a source of energy, sign-aiing instrument and :1. terminal plug, it trunl line teri'ninstii'ig in a s 'iringrjnfck at the same station with the eonnecting-eord, a plug at another station, a. repeating-coil having its windings inter 'iiosed in thotrunlr-line between said plug and spring-jack, a high-resistnnce signaling instrument in'circuit with the pen 'tion of the trunlvline extending to said springjack, (1 shunt-circuit around said higl'i-resistanee signaling instrument, and means for controlling said shunt to control the signaling instrument at the distant station of the trunkiine, substantially as described.

5. The combination. with a telephone-line, of a trunk-line and ii switch i'or unit ing said trunk-line with the telephonedine, u inding instrument at one terminal ot the trunk-line, a source of current com rooted with the trunkline, at higlnresistunee signaling instrument in a bridge of the trunk-line at the other terniinel thereof, a shunt shout sand high-resist- :ince signaling ii'istrnnient, sziid shunt controlling the operation ol' the firstmentioned signaling instrument and :i switch at the snhstation oi said line controlling snid shunt.

6. The combination with u'telcphone line, of a tlfilillidll'lfi, u switch for uniting sand trunk-line with said tele 'ihonedine, :1 source of current in u hridgo oi" the trunk-line tit one terininal thereoi', n high-resistance sign-sling instrument 1' in a hridgo ol' the trunl-;--line at the other terminal, zrslgnnl instrument: Z in said trunleline between the source of current and the signalingii'istruinent I, 21 shunt around;

said high-rcsistiincc signal ii'istruinei'u', it

switch at the substation ot said telephoneline controlling' said shunt, and it signaling instrument s in the shunt; Wherehy hotli sig neling instruments l and s are excited when said shunt closed.

and a switch for closing said circuit, u

l? and a circuit therefor, controlled. by relay Z", n highn'esistunci-i relay i included in stud signaling-circuit, signal v, eircuitiheretor, COIllJI'OllG-(t by said highiistance relay, shunt around the wind saidhigi'ionce relay, a relay 5 in said shunt, a signal 21., circuit therefor, controlled by said relay, a relay adopted when energized to close, the shunt about relay 1', a circuit for said relay q, and :i switch eontriiilting said circuit Where by upon the closure of the shunt about said. l'iig'h-resistnnce relay, hoth relays and 5 are excited to shunt out the signals associated therewith.

8. The combination with telephone-line, of it trunk-line having a. source of eulient connect ed therewith, a switch for uniting said trunk-line wit h sziid teleplmne-line, a. signal instrument zit. one terminal of the trunk line, it high-resistance igni'ding instrument in t he trunk-line for C(iililOiling the operation of the first-rueniirme l signaling ii'istrunient, a shunt shout said higlr-resistnnee signaling instrument, nnd 2t switch at the snijistetien l'or controlling said shunt.

ii. 'liie Combination with telephone-lines and t1 ti'iiiil;line tor uniting them, said trunklinc ha ing :i source of eurre it connect-ed therewith, of it signal in the trni iline at one terminal station, menus conductivehfsepnroting id. trunh iine into inductive K -eontinuous on o, ii high-resistnncc signnt-eonr trolling lil'W'ilCt in the tin ltdine, s id resistmice he ,3 suliicient to pr vent the operation ot said 1' ml, :1 s nnt ol said. magnet, and a relay in the trunk-lin odnptmil when said. trunleline is connected with the called line to control said shunt.

in witnes whereof I unto subscribe my name llllS 24th day o; n3", I 

